This capture is necessary, since it's not easy to defend the d6-pawn after
7. g1e2  7... a7a6  8. a2a4 This is useful to prevent …b7-b5 after an exchange of pawns on d5. 8... d8e7 A new move. To be honest, I don't quite understand what advantage Black has in delaying the inevitable moves that are the exchange on d5 or 0-0. 9. d5e6 Aronian decides to exploit Black's move order. Taking the knight to g3 or f4 and then completing development is also playable.